The best-selling erotic trilogy that follows the charged relationship between Anastasia Steele and the dominating billionaire Christian Grey is so steamy that it’s become known as “mummy porn”.

But author EL James has claimed that the popularity of her novels, which have now sold an incredible 31 million copies worldwide, is down to old-fashioned romance rather than sex.

‘It’s the love story. Women like to read a passionate love story. There is sex but as the books go on the sex changes as the relationship changes. You see the evolution of it,’ she said.

James also said she had been inundated with emails from readers who said the books had saved their marriages.

“Women of all ages are reading it – from women at university right through to women in their nineties,” she said. “I get the most TMI [too much information] emails you could ever hope for. People go and try this stuff.  It’s overwhelming. I wrote these books for me, but other people seem to share my fantasies too, so that’s interesting. I’m not such a pervert. It was a huge relief to find that out,” she joked.

James is married to Niall Leonard, a fellow writer, and has two teenage sons. She insists the character of Christian Grey is in no way based on her husband – Leonard’s first Christmas present to her was a tin-opener. “A tin opener! Jesus Christ on a bicycle. He never made that mistake again, trust me.”

Fifty Shades of Grey: The Classical Album a tie-in featuring music that “inspired” James’ writing and features in the books is now on release. It includes pieces by Chopin, Debussy and Rachmaninoff.

Image via Getty